'\" t
.\"     Title: uuidd
.\"    Author: [see the "AUTHOR(S)" section]
.\" Generator: Asciidoctor 2.0.20
.\"      Date: 2025-01-13
.\"    Manual: System Administration
.\"    Source: util-linux 2.40.4
.\"  Language: English
.\"
.TH "UUIDD" "8" "2025-01-13" "util\-linux 2.40.4" "System Administration"
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.SH "NAME"
uuidd \- UUID generation daemon
.SH "SYNOPSIS"
.sp
\fBuuidd\fP [options]
.SH "DESCRIPTION"
.sp
The \fBuuidd\fP daemon is used by the UUID library to generate universally unique identifiers (UUIDs), especially time\-based UUIDs, in a secure and guaranteed\-unique fashion, even in the face of large numbers of threads running on different CPUs trying to grab UUIDs.
.SH "OPTIONS"
.sp
\fB\-C\fP, \fB\-\-cont\-clock\fP[=\fItime\fP]
.RS 4
Activate continuous clock handling for time based UUIDs. \fBuuidd\fP could use all possible clock values, beginning with the daemon\(cqs start time. The optional argument can be used to set a value for the max_clock_offset. This gurantees, that a clock value of a UUID will always be within the range of the max_clock_offset.
.sp
The option \fB\-C\fP or \fB\-\-cont\-clock\fP enables the feature with a default max_clock_offset of 2 hours.
.sp
The option \fB\-C<NUM>[hd]\fP or \fB\-\-cont\-clock=<NUM>[hd]\fP enables the feature with a max_clock_offset of NUM seconds. In case of an appended h or d, the NUM value is read in hours or days. The minimum value is 60 seconds, the maximum value is 365 days.
.RE
.sp
\fB\-d\fP, \fB\-\-debug\fP
.RS 4
Run \fBuuidd\fP in debugging mode. This prevents \fBuuidd\fP from running as a daemon.
.RE
.sp
\fB\-F\fP, \fB\-\-no\-fork\fP
.RS 4
Do not daemonize using a double\-fork.
.RE
.sp
\fB\-k\fP, \fB\-\-kill\fP
.RS 4
If currently a uuidd daemon is running, kill it.
.RE
.sp
\fB\-n\fP, \fB\-\-uuids\fP \fInumber\fP
.RS 4
When issuing a test request to a running \fBuuidd\fP, request a bulk response of \fInumber\fP UUIDs.
.RE
.sp
\fB\-P\fP, \fB\-\-no\-pid\fP
.RS 4
Do not create a pid file.
.RE
.sp
\fB\-p\fP, \fB\-\-pid\fP \fIpath\fP
.RS 4
Specify the pathname where the pid file should be written. By default, the pid file is written to \fI{runstatedir}/uuidd/uuidd.pid\fP.
.RE
.sp
\fB\-q\fP, \fB\-\-quiet\fP
.RS 4
Suppress some failure messages.
.RE
.sp
\fB\-r\fP, \fB\-\-random\fP
.RS 4
Test uuidd by trying to connect to a running uuidd daemon and request it to return a random\-based UUID.
.RE
.sp
\fB\-S\fP, \fB\-\-socket\-activation\fP
.RS 4
Do not create a socket but instead expect it to be provided by the calling process. This implies \fB\-\-no\-fork\fP and \fB\-\-no\-pid\fP. This option is intended to be used only with \fBsystemd\fP(1). It needs to be enabled with a configure option.
.RE
.sp
\fB\-s\fP, \fB\-\-socket\fP \fIpath\fP
.RS 4
Make uuidd use this pathname for the unix\-domain socket. By default, the pathname used is \fI{runstatedir}/uuidd/request\fP. This option is primarily for debugging purposes, since the pathname is hard\-coded in the \fBlibuuid\fP library.
.RE
.sp
\fB\-T\fP, \fB\-\-timeout\fP \fInumber\fP
.RS 4
Make \fBuuidd\fP exit after \fInumber\fP seconds of inactivity.
.RE
.sp
\fB\-t\fP, \fB\-\-time\fP
.RS 4
Test \fBuuidd\fP by trying to connect to a running uuidd daemon and request it to return a time\-based UUID.
.RE
.sp
\fB\-h\fP, \fB\-\-help\fP
.RS 4
Display help text and exit.
.RE
.sp
\fB\-V\fP, \fB\-\-version\fP
.RS 4
Print version and exit.
.RE
.SH "EXAMPLE"
.sp
Start up a daemon, print 42 random keys, and then stop the daemon:
.sp
.if n .RS 4
.nf
.fam C
uuidd \-p /tmp/uuidd.pid \-s /tmp/uuidd.socket
uuidd \-d \-r \-n 42 \-s /tmp/uuidd.socket
uuidd \-d \-k \-s /tmp/uuidd.socket
.fam
.fi
.if n .RE
.SH "AUTHOR"
.sp
The \fBuuidd\fP daemon was written by \c
.MTO "tytso\(atmit.edu" "Theodore Ts\(cqo" "."
.SH "SEE ALSO"
.sp
\fBuuid\fP(3),
\fBuuidgen\fP(1)
.SH "REPORTING BUGS"
.sp
For bug reports, use the issue tracker at \c
.URL "https://github.com/util\-linux/util\-linux/issues" "" "."
.SH "AVAILABILITY"
.sp
The \fBuuidd\fP command is part of the util\-linux package which can be downloaded from \c
.URL "https://www.kernel.org/pub/linux/utils/util\-linux/" "Linux Kernel Archive" "."